What is the role of peritubular capillaries in kidney function?

Peritubular capillaries play a crucial role in kidney function by facilitating the reabsorption and secretion of various substances during the process of urine formation. These capillaries surround the nephron tubules, including both the proximal and distal convoluted tubules and the loop of Henle. As blood circulates through these capillaries, it is closely associated with the tubular fluid in the nephron.

This anatomical arrangement enables the efficient transfer of materials. For example, essential substances such as glucose, amino acids, and ions can be reabsorbed from the filtrate back into the bloodstream, ensuring that valuable resources are retained. Conversely, unwanted substances and excess ions can be secreted from the blood into the tubular fluid for excretion. This selective reabsorption and secretion process is vital for maintaining homeostasis, regulating blood volume, blood pressure, and the balance of electrolytes and other critical metabolites.